Is it possible to change view while using circle selection?
It is not, unfortunately.

It is a known limitation of the current modal operator's design. While a modal operator is running, like Circle Select, Border Select, Knife Tool, Move, Rotate, Scale, or any other, Blender can't modify the view.

The opposite is also true: while doing view transforms like Rotating the view or panning, no other tools can operate.

There were some rumors about overcoming this for future 2.8 versions but no definite decisions.